I need to refresh my Cache as soon as DB changes happened ,update might happen to DB from another source also not from my application in MySql. How can I do that as mysql will not provide access to call java method as part of TRigger as like in Oracle? (SpringBoot application)
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I'm here to ask you for a suggestion on which technology to use to add new features on an existing application based on Spring Boot.
The new features consist of some workflows, exposed as synchronous REST services, that must update the database and call REST services exposed by external applications, which consequently will update their own database.
For example, a service could implement this workflow:
insert rows in database
call the REST service of the application X, which will update its database
update rows in database
call the REST service of the application Y, which will update its database
update rows in database
This workflow must be synchronous and it is started from an human operator that will receive the outcome in few seconds.
If, for example, the step 4) fails, I need to:
make a compensation, calling another REST service of the application X, in order to undo what it made in step 2)
rollback the insert/update made in my database in steps 1) and 3)
Which technology, framework, tool or other would you use? In the past I implemented a similar scenario using Oracle SOA, but in this case I would avoid to introduce a new infrastructure in my application based on Spring Boot.
Thank you
I guess you need to learn a bit more about Spring Framework and Spring Boot.
1.insert rows in database : Spring Data JPA
2.call the REST service of the application X, which will update its database : A Http Client such as RestTemplate or WebClient
3.update rows in database : Spring Data JPA (again)
4.call the REST service of the application Y, which will update its database update rows in database : RestTemplate...
So so and so...
If you want to make a real workflow, you can use Activiti.
I have a Spring Boot application that uses MongoDB. My plan is to store data in a distributed caching system before it gets inserted into Mongo. If the database fails, the caching will have a queue and send to the DB once it is up. So, the plan is to make the caching layer in between the application and Mongo.
Can you suggest some ideas on how to implement this using Apache Ignite?
Take a look at write-behind cache store mode. It retries writing to the underlying database if insertion to the underlying DB fails. Let me know how it works for you.
You can also implement a custom CacheStore for an Ignite cache that will do the caching and enable write through for it. If the connection is lost, then you'll be able to collect entries in a buffer, while retrying to establish the connection back.
See more: https://apacheignite.readme.io/docs/3rd-party-store
My spring boot restful web services is working even though stopped running microsoft sqlserver database in my services. How does it work?
There might be below reason.
You might be using some kind of cache so still response is coming form cache even your db is down.
You might be checking services which are not required db transaction..
OR if you are only referring you application is continue to running then might be spring.datasource.continue-on-error=true has been set. or you might have some defined data source validations properties to at-least continue run app and whenever db is back, it will established a connection.
I have a particular instance of a class that loads some data from the database, so every time the database is updated the system should recreate the instance of that class to get the updated data
There are trivial several solutions:
(1) Use scheduling to load the latest data from DB periodically.
(2) Provide a web service such as RESTful API to load the latest data from DB.
(3) If your DB supports event-driven listeners, you can trigger your application to achieve this either by invoking a service described in (2) or send a message to queue and handle it by consumer.
I have been researching Spring Data Rest especially for cassandra and one of the questions my coworkers and I had was when does Spring Data connect to the database. We don't always want a rest controller to connect to the database so when does spring establish a connection if say we had a class extend the CRUDRepository? Does it connect to the database during the start of application itself? Is that something we can control?
For example, I implemented this example on Spring's website:
https://spring.io/guides/gs/accessing-data-rest/
At what point in the code does spring connect to the database?
Spring will connect to the DB as soon as the Datasource get initialized. Basically, Spring contexts will become alive somehow (Web listeners, manually calling them) and start creating beans. As soon as it reaches the Datasource, connection will be made and the connection pool will be populated.
Of course the above is based on a normal out of the box configuration and everything can be setup up to your taste.
So unless, you decide to control the connections yourself, DB connections will be sitting there waiting to be used.
Disagree with the above answer.
As part of research i initiated the datasource using a bean configuration and then changed my database password(not in my spring application but the real db username password)
The connection stays for a while and then in some point of time (maybe idle time) it stops working and throws credential exception.
This is enough to say the JPA does not keep the connection sitting and waiting to be used but uses some mechanism to occupy/release the db connection as per the need.